German soprano Anne Schwanewilms made headlines earlier this year after it emerged she had replaced another singer in a London opera production - reportedly because that soprano was too large for her role.

Deborah Voigt was dropped from this month's revival of Ariadne auf Naxos at the Royal Opera House after it was felt she would not suit the black evening gown her character wears in the modern dress production.

The American soprano made her displeasure clear to the press during a visit to London in March. "I have big hips and Covent Garden has a problem with them," she said.

And in a subsequent interview with America's National Public Radio network, she spoke of her "tremendous amount of disappointment in the Royal Opera House".

"We have to decide where the impetus of opera should be," she said.

Voigt said she was "disappointed" by the Royal Opera's decision

"It has traditionally been about a voice one does not find every day, and those voices come in packages that are not traditionally beautiful."

Schwanewilms, however, says that the visual aspects of a production should go hand in hand with musical considerations.

"You go into an opera house because you want to see something," she told BBC News Online. "Otherwise you would just stay at home and listen to a CD.

"In some cases it's nice to look at nice people on stage."

Schwanewilms says she had no idea she was replacing Voigt when she was offered the role of Ariadne in October 2002.

"I did not know at that time that Deborah Voigt was ever engaged," she said.

"My agent informed me later when I had already signed the contract."

Schwanewilms with Richard Margison in Ariadne auf Naxos

Schwanewilms, a freelance singer who specialises in the work of Richard Strauss, says she has some sympathy for her fellow performer.

"I haven't experienced this kind of thing myself yet, but I have heard from colleagues that it can happen," she said.

"If you are personally touched, if it happens to you, it must not feel very nice."

However, she insists such situations are "not so rare" in the world of opera.

"In these times things can change and they can decide to change the contract. It's always happened.

"The director thinks about the cast again, and he thinks, 'Oh no, five years ago we engaged these people'.

"The people who have the money have the power and they tell you what to do."

The production of Strauss' opera replaces togas with evening wear

It is a theme reflected in Ariadne auf Naxos, in which a one-act classical opera is preceded by a comic prologue that sees an opera company plagued by quixotic demands from their unseen patron.

The prologue was conceived in 1916 by Strauss and his librettist, Hugo von Hofmannsthal, after the original 1912 version was unsuccessful.

"Ariadne wasn't a success and they didn't get the money for it," Schwanewilms explains.

"So they made a joke of the people who didn't pay them by making fun of the real story."

The opera gives Schwanewilms the chance to play two roles: the eponymous princess, ossified by memories of the lover who deserted her, and the preening prima donna preparing to portray her on stage.

The soprano says the latter role, though exaggerated, is not far removed from reality.

"They exist, I promise!" she laughs. "And in some cases I can put my finger on my own chest and take a look at my own reactions.